SEOUL, July 4 -- North Korea fired three missiles off its eastern coast Saturday, South Korea said, in what was likely to be seen as a message of defiance to the United States on its Independence Day holiday.

The launches came two days after North Korea fired four short-range missiles, and could escalate tensions in the region as the United States tries to muster support for tough enforcement of the U.N. resolution imposed on Pyongyang for its May nuclear test.

South Korea's Joint Chiefs of Staff said the missiles were fired Saturday morning, but declined to elaborate on the type. Two missiles were fired early Saturday and a third was fired later in the morning, it said.

A senior presidential official told the Associated Press the missiles fired are believed to have a range of less than about 300 miles.

"Our military is fully ready to counter any North Korean threats and provocations based on strong South Korea-U.S. combined defense posture," the Joint Chiefs of Staff statement said.

The Japanese government condemned North Korea's action. In China, a foreign ministry spokesman said he had no immediate comment.

North Korea's state news agency carried no reports on the launches.

Speculation had been high that North Korea might launch more missiles. It had warned shipping to stay away from its east coast effective through July 10.

The senior presidential official cautioned that North Korea could fire more missiles in coming days, but said there is little possibility it could fire the intercontinental ballistic missile it threatened in April.

Saturday's launches came on July 4, or U.S. Independence Day. The North has a record of timing missile tests for that day.

"The missiles were seen as part of military exercises, but North Korea also appeared to have sent a message to the U.S. through the missile launches," the presidential official said, without elaborating.